This invention relates generally to attachments for conventional presses and, more specifically, to an unloader attachment which enters underneath a reciprocable ram to receive a workpiece as the workpiece is released from the press itself.
In the use of large presses in punching, blanking and stamping operations and the like, when a compound part is being prepared it is conventional for the compound part to remain attached to the die mounted on the reciprocable ram during the upstroke of the ram. At the top of the upstroke of the ram, a plurality of pins are contacted to release the workpiece. This is referred to as positive knock out of a workpiece and is conventional in this type of forming operation.
When the completely formed workpiece moves with the ram, once the workpiece has been released by a positive knock out, the workpiece falls under the influence of gravity and must be received by some type of unloading device. Prior to the present invention, a common technique was to have workmen reach in and grab the workpiece as it was being released from the ram.
The technology progressed to automated unloaders but these were not satisfactory for several reasons.
A first problem with prior art unloaders was the lack of synchronization of the movement of the unloader to the stroking of the press. The lack of synchronization typically resulted in contact between the unloader and the reciprocating ram, resulting in damage to the die mounted on the ram, to the unloader, and to the workpiece. A second problem was bouncing or vibrating of the unloader based upon the impact of the workpiece. This vibrating caused excessive wear to the unloader and often caused workpieces to bounce off of the unloader.
Hence the invention herein relates to an improved unloader for a conventional press which overcomes the foregoing problems. The present unloader is positively reciprocated by the press to maintain synchronization with the press stroke. The unloader includes a stationary support frame and a tray movably mounted on the support frame, and with the tray, as mounted, constrained for linear movement to eliminate bouncing and vibrating.